Noeggerathiales were until recently a group of plants with uncertain systematic position that existed in the Carboniferous and Permian times. Recent discoveries classify them as heterosporous progymnosperms. Despite the discovery of additional specimens, the group still remains highly artificial because their reproductive organs are rarely preserved in organic connection. Within the Carboniferous of Iberian Massif, the noeggerathialeans are poorly represented. Here, we describe Palaeopteridium andrenelii sp. nov. from the uppermost Carboniferous of Portugal. This is the second representative of Noeggerathiales reported in the Portuguese Carboniferous after Carlos Teixeira have described the noeggerathialean Rhacopteris gomesiana in the 1940s from Douro Carboniferous Basin (Stephanian C/lower Gzhelian, Upper Pennsylvanian). Palaeopteridium andrenelii was found in upper Asturian (upper Moscovian, Middle Pennsylvanian) strata from the classical Westphalian outcrops of Ervedosa, located in the region of Alto da Serra (Fânzeres), Gondomar, in northwestern Portugal. Two reproductive structures are associated with the frond of the new fossil species. Although not organically linked, both structures could belong to parent plant (frond) and represent possible detached macrosporangia. This reenforces the Palaeopteridium as a noeggerathialean and the first reproductive structures found for this genus.

The Vicissicaudata, a group of artiopods, originated and reached their highest diversity during the Cambrian period. However, relatively few vicissicaudatan species are known from the Paleozoic. Here we report a new species of vicissicaudatan arthropod, sister to the cheloniellids, from the Late Carboniferous Mazon Creek Lagerstätte. The two specimens preserve a small eyeless head, a trunk comprising seven tergites with wide pleural lobes, a narrower postabdomen bearing two long, posteriorly directed caudal appendages, and a short, shield-shaped telson. This new species not only extends the stratigraphic range of the Vicissicaudata into the Late Paleozoic but also represents an intermediate morphology between the cheloniellids and other vicissicaudatans.

Clastic sedimentary systems and their characteristics are assumed not to have been modified by carbonate bioclastic grains until the Phanerozoic. Here, we show that the presence of carbonate bioclasts produced by disintegrated biomineralizing metazoans modified fine-grained siliciclastic facies in the Late Ediacaran Tamengo Formation, Brazil, ca. 555–542 Ma. The analysis of both polished sections and thin sections shows that sand-sized carbonate bioclasts (< 2 mm) derived from the Ediacaran metazoan Corumbella created diverse sedimentary features later found in the Phanerozoic record, such as bioclastic-rich horizontal and low-angle cross-laminations, erosive pods and lenses, bioclastic syneresis cracks, ripples preserved by bioclastic caps, microbial lamination eroded and filled with bioclasts, and entrapped bioclasts within microbial mats. These sedimentary features would have hardly been recorded in fine siliciclastic facies without the sand-sized bioclasts. Based on these features, together with other sedimentary evidence, Corumbella depositional settings in the Tamengo Fm. are reinterpreted as mid-ramp, subtidal settings. The multi-component organization of the skeleton of Corumbella favoured disarticulation to yield a sand-sized bioclast, so in turn creating a new complexity to shallow marine clastic settings typical of Phanerozoic marine depositional systems.

This work reports the first data on the Variscan metamorphic evolution of the Marmarosh/Maramuresh massif in the Outer Eastern Carpathians. Geothermobarometry determinations coupled with U-Th-Pb dating of monazite, apatite, titanite and rutile were used to construct P-T-t paths and refine the geodynamic evolution of the pre-Alpine crystalline basement. These clockwise P-T-t paths evolve from 560–630 MPa and 515–535 °C to c. 900–1180 MPa in the north (Ukraine), while in the southern nappe (Romania), the P-T-t conditions evolve from 455–620 MPa and 545–555 °C, through to 670–745 MPa and 540–560 °C, to 910–965 MPa and 645–660 °C. The northernmost nappes were likely structurally lower relative to the southern nappes. Variscan progressive metamorphism related to nappe stacking climaxed at 350–340 Ma, as documented by U-Pb rutile and U-Th-Pb monazite dating.

In both regions, post-kinematic exhumation to 700–500 MPa, 550–630 °C MPa and then to the titanite stability field was dated at 317–327 Ma, using the U-Pb system on apatite and titanite. Subsequent Permian retrogression and exhumation was constrained to 280–290 Ma by U-Pb rutile and apatite and U-Th-Pb monazite dating. These data link the massif to the external zone of the Central European Variscides. We infer that all Variscan crystalline basement fragments in the Alps and Carpathians probably represent remnants of the same microcontinent, which was dismembered during Alpine orogenesis.

Paleoproterozoic granitoids of the lesser Himalayan belt are keys to understanding the evolution of the northern Indian continental margin and its position in the Columbia supercontinent assembly. We present whole-rock chemistry and zircon U-Pb geochronological data for Gwaldam Biotite Granite (GBGr) from the Baijnath Klippe (BK) in Kumaun Himalaya to elucidate their petrogenesis and geodynamic implications. Granites are characterized by ferroan, weakly peraluminous nature with high SiO2 and K2O contents, enrichment in LILE (Rb, Th, K and Pb), and depletion in Ba, Nb, P, Hf and Ti. Granites show enrichment in light rare earth element relative to heavy rare earth elements and pronounced negative Eu anomalies. Such chemistry suggests typical A-type granite with high Y/Nb >2 values that characterize it as A2-type granite. Zircon U-Pb ages for the granite yield upper intercept at 1900 ± 3 Ma (core) and 1854 ± 2 Ma (rim). Integrating the chemical and geochronological data, we propose a two-stage evolution model for the area. In the GBGr, the ∼1900 Ma date of zircon core is likely the date of crystallization of the melts presumably formed during the first extensional stage at uppermost mantle – lower crust levels caused by slab break-off/rollback, which followed a post-collisional setting. The second incipient rifting stage produced melt that entrained the zircon cores (∼1900 Ma) during its ascendance and crystallized as the GBGr at ∼1854 Ma when the zircon rims crystallized. It is further proposed that the Paleoproterozoic Northern Indian continental margin later underwent at least two crustal extensions during the Columbia supercontinent agglomeration.

The Lorne Plateau lava succession of the north-west Grampian Highlands of Scotland is an early component of post-collisional Late Silurian to Early Devonian magmatism in the Orthotectonic Caledonides emplaced in two phases between the Late Silurian (425.0±0.7 Ma U-Pb zircon) and the Siluro-Devonian boundary at ∼419 Ma. Palaeomagnetic study comprising thermal demagnetization and component analysis embracing the time frame of the preserved succession yields a coherent mean direction of magnetization from 58 sites (D/I = 43.7/−47.4°, α95 = 4.0°). A palaeomagnetic fold test is significantly positive with sills intruding unlithified sediment on the island of Kerrera confirming primary remanence. The ∼600 m thick succession has uniform normal polarity throughout permitting correlation with the beginning of a normal polarity chron extending from ∼426 to 403 Ma. The pole position at 2.7°N, 317.3°E (dp/dm = 3.8/5.8°) predicts a palaeolatitude of 26°S and corresponds precisely with remanence in contemporaneous rocks from the Midland Valley of Scotland. Regional palaeofield directions are evaluated in the context of transpressional moulding of the Acadian Orogeny on the Great Glen Fault system (~416−380 Ma).

The Early-Middle Jurassic impression/compression macroflora and the palynoflora from the Qaidam Basin in the northeastern Qinghai-Xizang (Tibetan) Plateau have been well studied; however, fossil wood from this region has not been previously documented systematically. Here, we describe an anatomically well-preserved fossil wood specimen from the Lower Jurassic Huoshaoshan Formation at the Dameigou section in northern Qinghai Province, northwestern China. This fossil exhibits typical Metapodocarpoxylon Dupéron-Laudoueneix et Pons anatomy with usually araucarian radial tracheid pits and variable cross-field pits, representing a new record for Metapodocarpoxylon in the Qaidam Basin. This discovery indicates that trees with this type of wood anatomy were not confined to northern Gondwana but also grew in more northerly regions in Laurasia. The wood displays distinct growth rings, with abundant, well-formed earlywood and narrow latewood. This observation, along with previous interpretations based on macroflora, palynoflora and sedimentological data, suggests that a warm and humid climate with mild seasonality prevailed in the region during the Early Jurassic.

This study presents new field and microstructural constraints into the batholith architecture and supra- to subsolidus evolution of late Variscan granitoids at Capo Vaticano Promontory, part of the ∼13 km-thick Serre Batholith in southern Italy. A field survey, assisted by petrographic analyses, produced the first geological map of the area (1:140,000 scale), detailing magmatic unit relationships and their petro-structural features. A migmatitic border zone (MBZ) marks the transition from lower-crustal paragneisses to the deepest emplaced granitoids. The oldest, deepest granitoids are strongly to moderately foliated amphibole-biotite tonalites and quartz diorites, transitioning to biotite tonalites and quartz-diorites (BT), which can be subdivided into strongly to moderately foliated (BTs) and weakly foliated to unfoliated (BTw). Clear intrusive contacts mark the passage from BTw to overlying weakly foliated-unfoliated porphyritic muscovite-biotite granodiorites and granites (PMBG). The study also revealed: a) a northern sector with a continuous batholith cross-section and b) a southern sector with an irregular distribution of the magmatic units due to post-Variscan tectonics. Microstructures document late Variscan deformation starting at suprasolidus conditions (e.g., quartz chessboard patterns and submagmatic fractures in plagioclase) and evolving through progressively high- to low-temperature subsolidus stages (e.g., feldspar bulging, quartz recrystallization, mica kinking) for all the magmatic units. Continuous supra- to subsolidus deformation associated with a well-developed fabric suggests tectonic control on the emplacement and cooling of early tonalites/quartz diorites, while the emplacement of the porphyritic granitoids has occurred during waning tectonic activity stages in the framework of the post-collisional evolution of the south-western Variscan Belt.

The integration of geotechnical and geophysical well logs, along with biostratigraphic and sediment analyses of borehole Schoten (northern Belgium), provides a better characterization of the glauconite-rich sandy Miocene successions near their type sections. It also provides a way to correlate the latter with more distal areas along the southern North Sea Basin. In the Schoten area, the Rupelian Boom Formation is unconformably overlain by the Lower to Middle Miocene Berchem Formation, which is in turn unconformably overlain by the Upper Miocene Diest Formation (Borsbeek Member). The Berchem Formation is formally subdivided into the Edegem, Kiel and Antwerpen members, which can be identified on the gamma-ray log of borehole Schoten. Sediment analyses show that the glauconite content and the local presence of phosphatic nodules are the main factors contributing to the fluctuating gamma-ray values. For the first time, the geophysical log signatures of the members of the Berchem Formation were correlated across large areas and major fault systems, which shows the regional significance of the boundaries between these members. Indeed, the boundary between the Edegem Member and the Kiel Member corresponds with the boundary between the Dutch Veldhoven and Groote Heide formations, known as the Early Miocene Unconformity. The overall higher gamma-ray values for the middle Miocene Antwerpen Member and equivalents in the upper part of the Dutch Groote Heide Formation are likely related to the eustatic sea level highs during the Miocene Climatic Optimum.

Trace fossils are described for the first time from the Purpurberg Quartzite of the Weesenstein Group, where deposition is so far considered to be glacio-eustatic controlled during the ∼565 Ma-old Weesenstein–Orellana glaciation. The mineralogically mature quartzites are locally rich in trace fossils, but the bedding plane bioturbation index is commonly less than 3. The trace fossil assemblage is of low diversity and comprises abundant Palaeophycus isp. and Palaeophycus tubularis and rare Phycodes, likely Phycodes cf. palmatus. One large Lockeia siliquaria and likely also a poorly preserved Rusophycus? isp. were found. Based on these findings and regional correlation with quartz-rich sequences of Saxo-Thuringia, an Early Ordovician age is suggested for the Purpurberg Quartzite, which can be regarded as a facies equivalent to shallow marine, quartz-rich sequences of southwestern Europe deposited along the northern Gondwanan margin during the Early Ordovician. In the light of this new insight, stratigraphic implications for the Weesenstein diamictite are also briefly discussed.

Continent formation and its stabilization are key factors for understanding tectonic processes and histories across geologic time. Sri Lanka consists of a Central Highland (HC) granulite/UHT terrane bounded by tectonic sutures and medium-to-high-grade magmatic arc terranes likely formed via Neoproterozoic double-sided subduction and collision associated with assembly of Gondwana. EMP Chemical Th-U-Pb dating of monazite within the eastern suture is dominated by 595–635 Ma dates, consistent with juxtaposition ca. 600 Ma as arc magmatism ended. Chemical analysis of metamorphic monazite dates from the eastern HC indicates prograde HT metamorphism (M1) at ca. 570 Ma during garnet growth (lower Y monazite) and retrograde HT metamorphism (M2) at ca. 560–550 Ma (higher Y monazite). These ages reflect orogenic thickening associated with arc collisions (M1) and retrograde metamorphism (M2) during deep-crustal exhumation of HC rocks. Regional long duration (>50–100 Ma) HT metamorphism, which continued until 520 Ma, and possibly to ca. 480 Ma, was followed shortly by rapid early Ordovician (480–490 Ma) lower to mid-crustal cooling based on near concordant 40Ar-39Ar hornblende and biotite ages. Rapid cooling occurred concurrently with metasomatism (He et al. 2016), and region-wide exhumation during orogenic collapse documented in adjacent portions of Gondwana. The cessation of long-duration HT metamorphism linked to the onset of rapid Ordovician intermediate-temperature (>500–<300 °C) cooling and exhumation via orogenic collapse resulted in young stabilized continental crust. The Neoproterozoic-Early Palaeozoic metamorphic/thermal evolution of Sri Lanka (and correlated regions) within Gondwana attests to the timing and process of rapid stabilization of central Gondwanaland.

The Imalia polyphase polymetallic deposit, located in the Mahakoshal belt of Central India, is hosted by carbonate rocks. The major part of mineralisation at Imalia results from hydrothermal activity induced by the intrusion of quartz porphyry dykes, which also formed an alteration halo of silicate and oxide minerals during their interaction with the host lithology. The initial silicates to form were hydrothermal Ca-amphibole and a minor amount of garnet, followed by potassic phases including biotite and K-feldspar, as well as rutile, apatite, titanite, pyrite, magnetite and rare calcite and ilmenite. A subsequent, cooler pulse of hydrothermal fluid overprinted the earlier-formed silicates and was responsible for the bulk of the sulphide mineralisation at Imalia. During this transformation phase, propylitic silicates primarily consisting of chlorite and epidote, along with a modest proportion of actinolite, albite, titanite, sericite and calcite, formed, accompanied by iron-rich oxide phases including magnetite, hematite and ilmenite. These silicates mostly formed under high water-to-rock ratios with significant meteoric water influence. Geothermometric and fluid inclusion data indicate that alteration zone minerals formed at temperatures between approximately 150°C and 550°C, at pressures of around 1 kbar and depths of less than 10 km, with a mean oxygen fugacity of log fO2 -32, closely aligned with the FMQ buffer. The alteration zone minerals record the evolution of hydrothermal fluids in a predominantly brittle structural regime, characterised by episodic decompression due to fluid overpressuring and hydrofracturing, as evidenced by various types of breccias, diverse quartz veins, open space-filling textures and fluid inclusion data.

We present a study of the Gyangarh and Anjana granitoids in the Aravalli Craton, northwestern India, with new data on their whole-rock geochemistry, U-Pb zircon and U-Th-total Pb monazite geochronology and structures and microstructures. These granitoids are monzogranites with metaluminous and calc-alkalic geochemical characters. They show negative Eu anomalies with depletions in Sr and Ti, indicating fractionation of plagioclase and Fe-Ti oxides from their parental magmas. U-Pb zircon dating of granitoids yielded crystallization ages of 1776 ± 35 Ma to 1709 ± 29 Ma, indicating that the plutons were emplaced during the late stages of the Aravalli orogeny. These plutons have been variably deformed and show shallow- to moderately dipping mylonitic foliations (<40°) with shallow (<30°) NW- to NE-plunging stretching lineations (SL1). The pole distribution of the mylonitic foliation (S1) and lineation (SL1) data indicates that the gentle mylonitic foliations have been overprinted by steep (>65°), NE-SW-striking S2 mylonitic foliations. The kinematic indicators suggest that the D1 and D2 deformations were associated with dextral-normal and sinistral-reverse senses of shearing, respectively. Monazite dating of texturally constrained grains shows that the pluton experienced intense mylonitization (D1-S1; 1653 ± 30 Ma) during the waning stages of the Aravalli orogeny. Later, these plutons experienced a second episode of mylonitization (933 ± 11 Ma to 897 ± 9 Ma) due to sinistral-reverse shearing (D2-S2) during the late stages of the Delhi orogeny. These new results show that the Gyangarh and Anjana plutons record signatures of two major orogenies that have shaped the Sandmata Complex (Aravalli Craton) in the Palaeoproterozoic.

Advances in analytical instrumentation over the past decade have facilitated the development of new geochronological methods. In particular, the triple quadrupole inductively coupled plasma mass spectrometers with in-line reaction cells have made it possible to investigate beta decay geochronological systems, including Lu-Hf in garnet, in situ via laser ablation. While these new methods allow different kinds of studies to be carried out, their utility relative to well-established methods has not been investigated in detail. Herein we present the results of in situ garnet Lu-Hf and monazite U(-Th)-Pb geochronological analyses of two adjacent Archean meta-pelitic rocks from the Northwest Territories, Canada. Whereas the garnet Lu-Hf analyses define single population isochrons of ca. 2570 Ma, monazite U(-Th)-Pb analyses define two chemically distinct populations. An older ca. 2570 Ma monazite population has low Y concentrations, while a younger, ca. 2530 Ma monazite population has high Y concentrations. The change in Y concentrations in the monazite is consistent with coeveal growth with garnet during prograde metamorphism whereas the younger high Y monazite is interpreted to reflect growth during garnet breakdown during decompression. The results presented herein demonstrate that incorporating both in situ garnet and monazite geochronological data takes advantage of each method (i.e. the spatial precision, variable (re)crystalization under different conditions, and the ability to determine a date without relying on an isochron for monazite U-Pb, and the ability to date a primary metamorphic phase for garnet Lu-Hf) to build a more robust geochronological history.

A previous study of the altitudes of the lowest part of the Upper Cretaceous–Eocene stratigraphic ensemble evidenced for the first time the existence of an east-west elongated dome between N53° and N54° Lat. on the western slope of the Southern Urals. This ridge which is superimposed on the remnants of the Sernovodsk–Abdullino Aulacogen and with the Belaya tear fault was the result of the rejuvenation of these deep basement features; it has been interpreted as a positive flower structure. Slightly to the north, the Southern Urals display a clear bend towards the East. In front of it, detailed microstructural studies show that this curvature was associated with a stress pattern typical of an indentation. Field studies concentrating on the intersection between the flower structure and the Belaya River Valley show (1) that there are two riverbeds more or less superimposed in the same valley, (2) that the older watercourse is offset by small east-west shear zones, (3) that the shear zones are in continuity with the flower structure and (4) that the recent riverbed is not affected by similar offsets. The vertical movements recorded along the Belaya River by geodetic measurements don’t support the existence of a recent activity of the indenter because they are always of a limited extent and associated with karst collapses. This conclusion is supported by the stratigraphic evolution of the fluvial sediments and confirms that the indentation of the Southern Urals did not continue after 10 ka.

Nd-Hf isotope evolution in arc magmas has been widely used to trace the advance and retreat of subduction zones over time. However, the reliability of this method has been questioned. One way to assess its validity is by comparing it with LaN/YbN or Sr/Yb ratios, which are well-established proxies for crustal thickness. In this study, we present new Nd-Hf isotopic data from the Permian to Triassic Hangay Batholith in the western Mongol-Okhotsk Orogen (Hangay Mountains), to evaluate the role of Nd-Hf isotopes in tracing crustal thickness variations along convergent plate boundaries. Our results show that granitoids from the Hangay Batholith likely originated from partial melting of crustal materials, with a possible mantle contribution. These granitoids have moderate εNd(t) and εHf(t) values, with no significant shift from Permian to Triassic, which contrasts with the continuous crustal thickening indicated by LaN/YbN ratios. This inconsistency between Nd-Hf isotope evolution and crustal thickness variation is likely due to the heterogeneous crustal architecture in this accretionary orogen. Our findings highlight the need for caution when linking Hf and Nd isotope evolution with extensional and contractional tectonics.

The Iberian Pyrite Belt contains one of the largest accumulations of massive sulphide deposits on Earth. Many of these deposits are hosted by latest Devonian black shales rich in terrestrial and marine palynomorphs. Among the marine fossils, the most abundantly reported species is Maranhites mosesii. By means of a multi-analytical methodology, including (1) biometry of specimens, (2) TOFSIMS imaging and spectral analysis of selected specimens and (3) host-rock geochemistry, we detected that cysts of M. mosesii are smaller and lighter in massive sulphide-generating environments than in coeval non-massive sulphide-generating environment. Cysts of M. mosesii sank after encystment and maturated in the seafloor of different subbasins affected by disparate anoxic conditions. The specimens that maturated in anoxic settings enriched in pollutants, like Arsenic (As) and Lead (Pb), were smaller and lighter than those from non-polluted anoxic environments. Their organic walls were also enriched in As. Neither the anoxia nor the pollutants prevented the proliferation of M. mosesii, as this was the most abundant phytoplanktonic species in all environments. To explain this, we suggest that this species developed a successful adaptive mechanism that might involve anaerobic metabolic interchange with the surrounding oxygen-depleted media and high levels of tolerance to stressors. Whatever the reason, it entails a causal relationship between cyst size and seafloor environmental conditions. In consequence, the biometry of M. mosesii can be envisaged as a promising vector for sulphide deposit exploration in the Iberian Pyrite Belt.

Dating the shear zone activity remains challenging and depends on geochronometer reactivity. We investigate the Forno-Rosarolo Shear Zone (Ivrea-Verbano Zone, Italy), developed in the intermediate-low continental crust under amphibolite-facies conditions. Sheared paragneisses and calc-silicates were dated using in situ U–(Th–)Pb monazite and titanite geochronology. Three monazite generations (MNZI-III) were identified based on microstructural position, internal features, chemical zoning (Th, Y) and isotopic data. Deformation was mainly recorded by MNZII, with high-Y domains yielding Triassic dates (average ages of: 238±8 and 222±8 Ma). Rare, highly fractured or porous MNZIII grains provided younger dates (202±8 to 184±6 Ma). MNZI, abundant in protomylonites, retains regional metamorphism, linking monazite U–Th–Pb data to fabric evolution. Titanite shows different zoning features and chemistry as a function of the surrounding mineral assemblage: (i) strongly zoned grains are mostly associated with silicate-rich layers; (ii) homogeneous grains are generally within the silicate-poor layers. Both types show a decoupling between chemistry, almost completely related to the peak metamorphism, and U–Pb isotopes. Deformation microstructures promoted a total reset of the U–Pb dataset at the beginning of deformation and a subsequent volume diffusion through the grains: the innermost domains of both titanite types provide a Triassic lower intercept age (240±5 Ma) while the rims/tips, locally coinciding with high strained portions, define an alignment of isotopic data with a Jurassic lower intercept age (186±6 Ma). This study highlights how combining monazite and titanite geochronology refines the timing and duration of deformation, particularly in large-scale shear zones involving different lithologies.

The Lower Jurassic (Toarcian) Posidonienschiefer Formation of southwestern Germany is a classic konservat lagerstätte, yielding some of the world’s best-preserved fossils of marine vertebrates, including ichthyosaurs, thalattosuchian crocodylomorphs, plesiosaurs and fishes. Despite numerous studies concentrating on the taphonomy of ichthyosaurs in this formation, less taphonomic work has focussed on the thalattosuchians of the assemblage. Multiple thalattosuchian species displaying a wide range of body sizes have been recovered. We investigated indicators for seafloor arrival position in thirteen Macrospondylus bollensis and one Platysuchus multiscrobiculatus specimens representing various body sizes using three-dimensional (3D) photogrammetric models. False-colour depth maps were used to interpret the relative topography (depth level) of bone penetration into the sediment and were aligned on the XY plane, making them parallel to the stratigraphic plane. Our results show both headfirst and non-headfirst seafloor arrivals in observed specimens, with headfirst seafloor arrivals exhibiting deeply buried skulls, displacement of select cervical vertebrae and/or characteristic fractures in the cranium and mandible. We (1) interpret seafloor landing types in teleosauroids; (2) recognize and list specific characteristics that are consistently attributed to either a headfirst or non-headfirst seafloor arrival; (3) discuss possible factors that may have contributed to these features, such as body shape and size, substrate and velocity; and (4) provide a new definition for headfirst seafloor arrival that can be readily attributed to other marine vertebrates from various formations. Lastly, our results show that observers must carefully consider how historical specimens might have been prepared, as this may influence taphonomic interpretations.

The Eastern Ghats Belt (EGB) has been extensively studied by the geoscientific community; however, this communication reports unique mineral assemblages that have not been documented previously. This study documents the occurrence of sapphirine, spinel, orthopyroxene, sodic-gedrite, calcic-amphibole, biotite and plagioclase assemblage indicating in ultrahigh temperature (UHT) metamorphic conditions. The significance of this study lies in the peculiarity of sapphirine being present within anorthite matrix which has been reported for the first time from the Indian subcontinent. The studied assemblage has been correlated with the more or less similar assemblage of rock called ‘Sakenites’ reported from southern Madagascar to correlate the most probable source rock ‘anorthosites’ that underwent metamorphic transformations and led to the unique UHT mineral assemblage. The Na-rich gedrite identified within the assemblage represents a relict mineral indicative of high-grade amphibolite-facies metamorphism. The derived pressure–temperature (P-T) trajectory reveals a decompression path with almost uniformly decreasing P-T conditions in contrast to the commonly reported isothermal decompression (ITD) path from various other domains and provinces of the EGB. The corresponding retrograde assemblage has been recalibrated by the sequential removal of sapphirine and corroborated with T-X (H2O) constraints.

The analyzed EMP U-Th-Pb monazite chemical age constraints suggest mesoproterozoic to neoproterozoic episodes corresponding to a pair of ∼959 Ma and ∼846 Ma thermal events. These metamorphic events have been correlated to reconstructing the Rodinian supercontinent at ∼959 Ma and the initiation of its subsequent break-up at ∼846 Ma.